In short, yes they are. Using bubblewrap[1] and some code recycled from flatpak. Nowdays when you run linux native game on steam you're using containerization tool called pressure-vessel[2], which have names like soldier, spy, sniper from team fortress and you can select them from the compability tab, some of them might not be installed by default and older runtimes didn't use containers. I tried with Wesnoth (which is free open source game since I didn't have Symphony) to see if it would load/save data from another place. Running with 3.0 (sniper) and it seems to work. PRESSURE_VESSEL_FILESYSTEMS_RW=/stash %command% --userdata-dir /stash/wesnoth/1.18 So in steam right click game -> properties -> general -> launch options and set: PRESSURE_VESSEL_FILESYSTEMS_RW="/path/to/dir" %command% you can spawn shell also instead of starting the game to check things out PRESSURE_VESSEL_FILESYSTEMS_RW="/path/to/dir" PRESSURE_VESSEL_SHELL=instead %command% If you only need to read and not write, use PRESSURE_VESSEL_FILESYSTEMS_RO there is also legacy STEAM_COMPAT_MOUNTS. Not exactly sure about the differences I would stick with the former, there's more docs[3] if something goes wrong. [1] https://github.com/containers/bubblewrap [2] https://gitlab.steamos.cloud/steamrt/steam-runtime-tools/-/blob/main/docs/co... [3] https://gitlab.steamos.cloud/steamrt/steam-runtime-tools/-/tree/main/docs